Troy Lee Designs A3 Mips Enduro / MTB Mountain Cycling Helmet

So comfortable you won't ever want to take it off. The Troy Lee A3 MTB helmet is a high quality mountain bike helmet with luxurious comfort, patent-pending innovations in safety, ventilation that will you keep you cool on the longest climbs with comfort and coverage to protect on the sketchiest of descents.
Highest possible score (5-STAR) from Virginia Tech helmet safety lab so you can feel confident in all conditions.
Key Features:
- The latest evolution in TLD trail helmets with MIPS Technology
- Adjustable visor with goggle storage and Automatic Magnet System
- EPS and EPP for high-speed and low-speed impact energy management
- Smart shear visor screws to prevent damage to the helmet
- TLD V3 precision fit with 3 levels of height adjust
- TLD’s deepest coverage half shell helmet
- 16 vents with optimised channelling for breathability
- Removeable Sweatglide system for hygiene
- 2-piece antimicrobial and quick dry liner
- V2 Fidlock-Magnetic Buckle
- Weight: ~375g
Safety is front and centre with the Troy Lee A3 MIPS MTB trail helmet. The helmet is made from EPS and EPP foams for equal protection across high and low-speed impacts. The A3 uses MIPS technology to offer the best protection. The A3 also extends lower than previous TLD helmets, to offer the best lower head coverage.
Every detail of the TLD A3 has been obsessed over. The adjustable visor has goggle storage and attaches in three positions with magnets, so it is easy to move as well as avoiding any small parts breaking. The helmet closes with a V2 Fidlock-Magnetic Buckle for easy on and off. TLD has also made sure the helmet works with a vast array of optics making it a great choice for riders, regardless of eyewear choice.
Occasionally, without notice, manufacturers change product design and/or specifications.
Troy Lee Designs A3 Mips Size Guide
Size |
Centermeters |
Inches |
YTH/XS |
48 - 54 | 19 - 20 7/8 |
S/M |
54 - 56 |
21 1/4 - 22 |
M/L |
57 - 59 |
22 3/8 - 23 1/4 |
XL/XXL |
60 - 62 |
23 5/8 - 24 3/8 |
How to measure
To find the circumference of your head, place a tape measure in the centre of your forehead, wrap it around above your ears and around the back of your head. If there's a slight difference between two different sizes, always go for the tighter size.

Once you know the circumference of your head, see the available sizes shown on the product and select the appropriate one.
The majority of cycling helmets have some form of adjustment for size, usually in the form of a ratchet adjuster to tighten or loosen the straps, some helmets will also come with different thickness pads to further customise the fit.
Read our clothing size guide for more information on sizing.
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